Docker高级应用之动态绑定卷组

之前介绍过Docker高级应用之动态扩展容器空间大小（地址：http://www.linuxidc.com/Linux/2015-01/112245.htm），本次介绍如何动态的绑定卷组。

为什么使用卷组呢，比如想把物理机里的目录给予容器共享，或者把物理机的一个目录作为共享目录，做日志搜集等等功能。

默认docker添加卷组是在启动容器的使用使用-v参数

-v, --volume=[]            Bind mount a volume (e.g., from the host: -v /host:/container, from docker: -v /container)

举例 物理机目录/data/software想挂载到容器的/tmp/software里 其中/data/software内容是 15:21:14 # ll /data/software/ total 19692 -rw-r--r--  1 root root    1940 Nov 10 20:42 CentOS-Base-6.repo -rwxr-xr-x  1 root root 12752168 Nov 10 14:15 etcd -rwxr-xr-x  1 root root  7400424 Nov 10 14:15 etcdctl drwxr-xr-x 21 1000 1000    4096 Oct 29 02:06 systemd-217

启动docker的命令是

docker run -d -p 22  --name="test" -v /data/software:/tmp/software  docker.ops-chukong.com:5000/centos6-http:new /usr/bin/supervisord

下面是做绑定测试 root@docker-test2:/tmp 15:29:23 # docker run -d -p 22  --name="test" -v /data/software:/tmp/software  docker.ops-chukong.com:5000/centos6-http:new /usr/bin/supervisord a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf root@docker-test2:/tmp 15:31:15 # docker-enter test sh -c "ls -l /tmp/software" total 19692 -rw-r--r--  1 root root    1940 Nov 10 20:42 CentOS-Base-6.repo -rwxr-xr-x  1 root root 12752168 Nov 10 14:15 etcd -rwxr-xr-x  1 root root  7400424 Nov 10 14:15 etcdctl drwxr-xr-x 21 1000 1000    4096 Oct 29 02:06 systemd-217 root@docker-test2:/tmp 15:31:21 # docker-enter test sh -c "mount" rootfs on / type rootfs (rw) /dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf on / type ext4 (rw,relatime,discard,stripe=16,data=ordered) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=65536k) /dev/sdb1 on /.dockerinit type ext4 (rw,relatime,data=ordered) /dev/sda3 on /etc/resolv.conf type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /etc/hostname type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /etc/hosts type ext4 (rw,relatime,data=ordered) /dev/sda3 on /tmp/software type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /.dockerenv type ext4 (rw,relatime,data=ordered) devpts on /dev/tty1 type devpts (rw,relatime,gid=5,mode=620,ptmxmode=000) devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666) devpts on /dev/ptmx type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666) root@docker-test2:/tmp 15:31:28 # docker-enter test sh -c "df -h" Filesystem            Size  Used Avail Use% Mounted on rootfs                9.8G  470M  8.8G  5% / /dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf                       9.8G  470M  8.8G  5% / shm                    64M    0  64M  0% /dev/shm /dev/sdb1            1.8T  22G  1.7T  2% /.dockerinit /dev/sda3            518G  457G  35G  93% /etc/resolv.conf /dev/sdb1            1.8T  22G  1.7T  2% /etc/hostname /dev/sdb1            1.8T  22G  1.7T  2% /etc/hosts /dev/sda3            518G  457G  35G  93% /tmp/software /dev/sdb1            1.8T  22G  1.7T  2% /.dockerenv

可以看到挂载完成，并且容器里的/tmp/software与/data/software里内容一致 但上面只是在创建并启动容器的时候可以挂载卷组，如果允许中的如何挂载呢？ 具体知识可以参考http://jpetazzo.github.io/2015/01/13/docker-mount-dynamic-volumes/ 下面是修改的脚本 内容为 #!/bin/bash #This script is dynamic mount docker volumens #Author Deng Lei if [ -z $1 ] || [ -z $2 ] || [ -z $3 ]; then     echo "Usage: container_name physics_volumes container_volumes"     echo "Example: I want mount physics /tmp/test to container /src in test"     echo "The command is: bash `basename $0` test /tmp/test /src "     exit 1 fi which nsenter &>>/dev/null if [ $? -ne 0 ];then     echo "plsease install nsenser,command is:yum install util-linux"     exit 1 fi set -e CONTAINER=$1 HOSTPATH=$2 CONTPATH=$3 if [ ! -d $HOSTPATH ];then     echo "physics $HOSTPATH is not exist!"     exit 1 fi REALPATH=$(readlink --canonicalize $HOSTPATH) FILESYS=$(df -P $REALPATH | tail -n 1 | awk '{print $6}') while read DEV MOUNT JUNK     do         [ $MOUNT = $FILESYS ] && [ $DEV != "rootfs" ] && break     done </proc/mounts [ $MOUNT = $FILESYS ] # Sanity check! while read A B C SUBROOT MOUNT JUNK     do [ $MOUNT = $FILESYS ] && break     done < /proc/self/mountinfo [ $MOUNT = $FILESYS ] # Moar sanity check! SUBPATH=$(echo $REALPATH | sed s,^$FILESYS,,) DEVDEC=$(printf "%d %d" $(stat --format "0x%t 0x%T" $DEV)) PID=$(docker inspect --format "{{.State.Pid}}" "$CONTAINER") run_command="nsenter --target $PID --mount --uts --ipc --net --pid -- sh -c" if  [ `$run_command "mount|grep $CONTPATH|wc -l"` -ne 0 ];then     echo "container $CONTAINER mount dir $CONTPATH is mounting!"     exit 1 fi $run_command "[ -b $DEV ] ||mknod --mode 0600 $DEV b $DEVDEC" $run_command "mkdir /tmpmnt" $run_command "mount $DEV /tmpmnt" $run_command "mkdir -p $CONTPATH" $run_command "mount -o bind /tmpmnt/$SUBROOT/$SUBPATH $CONTPATH" $run_command "umount /tmpmnt" $run_command "rmdir /tmpmnt" check_result=`$run_command "mount|grep $CONTPATH|wc -l"` if [ $check_result -ne 0 ];then     echo "dymainc mount physics $HOSTPATH on $CONTAINER $CONTPATH is success!" else     echo "dymaninc mount physics $HOSTPATH on $CONTAINER $CONTPATH is fail!" fi

然后在给已经存在的test容器里新挂载一个卷组，把本地的/data/docker-dir挂载到/tmp/docker-dir 当前物理机/data/docker-dir里内容是 root@docker-test2:/tmp 15:37:17 # ll /data/docker-dir/ total 4 -rw-r--r-- 1 root root 0 Feb 11 09:31 a -rw-r--r-- 1 root root 2 Feb 11 09:31 b

挂载的方法是

15:38:28 # sh dynamic_mount_docker_volume.sh Usage: container_name physics_volumes container_volumes Example: I want mount physics /tmp/test to container /src in test The command is: bash dynamic_mount_docker_volume.sh test /tmp/test /src

第一个参数是容器名，第二个参数的物理机的目录，第三个参数是挂载到容器里的目录 进行挂载

root@docker-test2:/tmp 15:36:14 # sh dynamic_mount_docker_volume.sh test /data/docker-dir/ /tmp/docker-dir dymainc mount physics /data/docker-dir/ on test /tmp/docker-dir is success!

可以看到成功的挂载了 下面做一下测试

15:37:28 # docker-enter test sh -c "ls -l /tmp/docker-dir" total 4 -rw-r--r-- 1 root root 0 Feb 11 09:31 a -rw-r--r-- 1 root root 2 Feb 11 09:31 b root@docker-test2:/tmp 15:38:18 # docker-enter test sh -c "mount" rootfs on / type rootfs (rw) /dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf on / type ext4 (rw,relatime,discard,stripe=16,data=ordered) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=65536k) /dev/sdb1 on /.dockerinit type ext4 (rw,relatime,data=ordered) /dev/sda3 on /etc/resolv.conf type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /etc/hostname type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /etc/hosts type ext4 (rw,relatime,data=ordered) /dev/sda3 on /tmp/software type ext4 (rw,relatime,data=ordered) /dev/sdb1 on /.dockerenv type ext4 (rw,relatime,data=ordered) devpts on /dev/tty1 type devpts (rw,relatime,gid=5,mode=620,ptmxmode=000) devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666) devpts on /dev/ptmx type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666) /dev/sda3 on /tmp/docker-dir type ext4 (rw,relatime,data=ordered) root@docker-test2:/tmp 15:38:24 # docker-enter test sh -c "df -h" Filesystem            Size  Used Avail Use% Mounted on rootfs                9.8G  470M  8.8G  5% / /dev/mapper/docker-8:17-37748738-a21506d7b36e04e091008f4a326ac17c94e3d855e3aadb52992d7ba95f45cbbf                       9.8G  470M  8.8G  5% / shm                    64M    0  64M  0% /dev/shm /dev/sdb1            1.8T  22G  1.7T  2% /.dockerinit /dev/sda3            518G  457G  35G  93% /etc/resolv.conf /dev/sdb1            1.8T  22G  1.7T  2% /etc/hostname /dev/sdb1            1.8T  22G  1.7T  2% /etc/hosts /dev/sda3            518G  457G  35G  93% /tmp/software /dev/sdb1            1.8T  22G  1.7T  2% /.dockerenv /dev/sda3            518G  457G  35G  93% /tmp/docker-dir

可以看到已经动态的挂在上了，并且挂在后目录里的内容一致 如果挂载的时候，第一个参数，容器不存在会报以下错误

16:23:27 # sh dynamic_mount_docker_volume.sh  test123 /data/docker-dir/ /src Error: No such image or container: test123

如果挂载的时候，第二个参数，物理机的被挂载的目录不存在，会报错

root@docker-test2:/tmp 15:39:18 # sh dynamic_mount_docker_volume.sh  test /tmp/sfsdfdf1 /src physics /tmp/sfsdfdf1 is not exist!

如果挂载的时候，第三个参数，容器的挂载的目录已经被挂载了，会报错

12 15:44:25 # sh dynamic_mount_docker_volume.sh  test /data/software/ /src container test mount dir /src is mounting!

上面就是介绍如何动态的绑定卷组，只是一种方法，不太建议使用，有问题请留言。